ASN Lookup
Find the Autonomous System by IP address or AS number.
ASN Lookup retrieves the Autonomous System Number for an IP or domain. Shows hosting provider, country, ASN size, prefix. Useful for identifying companies behind IPs, BGP analysis, discovering connected services.
Announced Prefixes
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How it works
Enter IP or AS number
Look up BGP tables
Get AS data and prefixes
What is an ASN?
ASN (Autonomous System Number) is a unique number assigned to ISP networks, CDNs, and large organizations. By ASN you can identify the IP range owner and track traffic routing.
Search by ASN and IP
Enter AS number or IP — get complete information about the autonomous system.
IP Prefixes
List of all IPv4 and IPv6 subnets announced by this autonomous system.
BGP Peers
Upstream providers and peering connections for this AS.
AS Reputation
Abuse indicators: spam, DDoS sources, known malicious hosts.
Who uses this
DevOps
routing diagnostics
Security
attack source analysis
Network engineers
BGP peer analysis
Developers
CDN identification
Common Mistakes
Best Practices
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ASN lookup history and BGP route change monitoring.
Sign up freeWhat is an ASN and How Does Internet Routing Work?
An Autonomous System Number (ASN) is a unique identifier assigned to a network or group of networks managed under a single routing policy. ASNs are used in BGP (Border Gateway Protocol) to exchange routing information between organisations on the internet. Knowing the ASN of an IP address helps identify its owner, hosting provider, geographic region, and network operator — useful for security investigations, traffic analysis, and blocking malicious ranges at the network level.
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Frequently Asked Questions
What is an ASN?
ASN (Autonomous System Number) is a unique network identifier on the internet. Each ISP has one or more ASNs.
How to find ASN by IP?
Enter an IP address in the check field — we show the ASN, organization name, country, and IP range.
Why use ASN Lookup?
To identify the provider, analyze network infrastructure, investigate security incidents, and geolocate IPs.
Related guides
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